biological molecules Flashcards
what are carbohydrates?
organic compounds made of hydrogen, carbon, and oxygen
Organic compounds are the primary constituents of living organisms.
what are monosaccharides?
monomers that compose other carbohydrates
They are the simplest form of carbohydrates.
what the 2 isomers of glucose?
structurally different
α-glucose (hydroxyl group above) and β-glucose (hydroxyl group below)
α-glucose has a hydrogen above the right carbon, while β-glucose has it below.
what is a disaccharide?
formed when 2 monosaccharides join in a condensation reaction, forming a glycosidic bond and releasing a molecule of water
This process releases a molecule of water.
what is maltose composed of?
α-glucose + α-glucose
It is a type of disaccharide.
what is sucrose composed of?
α-glucose + fructose
Commonly known as table sugar.
what is lactose composed of?
α-glucose + galactose
It is the sugar found in milk.
what is a polysaccharide?
many monosaccharides joined in many condensation reactions
They are well suited for energy storage or structural functions.
what is starch?
a glucose polysaccharide found in photosynthesisng / storage cells of plants
amylose -> unbranched helical chain with 1. 4 glycosidic bonds
amylopectin -> branched chain with 1.4 and 1.6 glycosidic bonds
It is coiled and compact, making it efficient for storage.
why are a glucose polysaccharides well suited for energy storage?
→ helical so coiled and compact
→ branched so glucose accessible for hydrolysis for respiration
→ large and insoluble so not osmotic effect and can’t cross cell membrane
It is one of the components of starch.
what is glycogen?
a glucose polysaccharide in animal cells with high metabolic rate
highly branched with 1.4 and many 1.6 glycosidic points so many accessible points
It is highly branched to provide many accessible points for hydrolysis.
how do you perform a quantitative glucose concentration test?
- produce a dilution series with range of concentrations
- produce a calibration curve
- perform the Benedict’s test
- use a colorimeter to measure absorbance
- plot against the calibration curve to calculate concentration
This method allows for accurate measurement of glucose concentration.
what is cellulose
structural b glucose polysaccharide
main component of plant cell walls
Cellulose provides structural support in plant cell walls.
describe and explain the structure of cellulose
→ long straight chain of b glucose with 1.4 glycosidic bonds between alternating inverted molecules
→ hydrogen bonds form cross linkages between hydroxyl groups in parallel chains → high tensile strength
→ microfibrils → macro-fibrils provide rigidity
describe how you would carry out a reducing sugars test
- heat Benedict’s reagent and sample
- observe color change from blue to red/orange
A positive result indicates the presence of reducing sugars.
describe how you would carry out a non-reducing sugars test
- reducing sugars are negative
- boil sample with acid to break glycosidic bonds
- neutralize with alkali
- heat with Benedict’s reagent
- observe color change from blue to red
This method breaks glycosidic bonds to test for non-reducing sugars.
